(1) Field of the Invention
The present invention relates to a speech synthesis apparatus which synthesizes speech corresponding to a text and outputs the synthesized speech, and in particular, to a speech synthesis apparatus for naturally reading out even incomplete sentences.
(2) Description of the Related Art
Conventionally, a speech synthesis apparatus which generates synthesized speech corresponding to a desired text and outputs the synthesized speech has been provided. As an application field, there is a use of enabling a user to listen to synthesized speech corresponding to the contents of e-mail instead of reading the e-mail itself which is written in text format.
However, a text of e-mail includes symbols such as citation symbols in the citation section and the signature section unlike texts of a novel and a newspaper article, and such symbols cannot be read out in a usual manner. Therefore, there is a need to modify these symbols appropriately so as to make them readable. Patent References 1 and 2 are example techniques for this purpose.
Patent Reference 1: Japanese Patent Publication No. 9-179719 (pages 7 to 8 of the description).
Patent Reference 2: Japanese Patent Publication No. 2003-85099 (pages 22 to 24 of the description).
The method of Patent Reference 1 makes it possible to circumvent the difficulty in reading out the citation text by, for example, eliminating a citation symbol which does not need to be read out and reading out only the citation text, or eliminating the whole citation section.
In addition, the method of Patent Reference 2 makes it possible to process the citation section in a more appropriate manner, more specifically, to collate a citation text with the character strings included in the accumulated texts of already-read e-mail and delete the citation section only in the case where the citation text is included in the texts of already-read e-mail.